RADIO AIDS TO MARINE NAVIGATION - Canadian Coast Guard
RADIO AIDS TO MARINE NAVIGATION - Canadian Coast Guard
RADIO AIDS TO MARINE NAVIGATION - Canadian Coast Guard
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TABLE 3<br />
U.S. WEST COAST LORAN-C CHAIN – GRI 9940<br />
STATION<br />
FALLON,<br />
Nevada (1)<br />
GEORGE,<br />
Washington (1)<br />
MIDDLE<strong>TO</strong>N,<br />
California (1)<br />
SEARCHLIGHT,<br />
Nevada (1)<br />
LATITUDE<br />
LONGITUDE<br />
(2)<br />
39 33 06.74N<br />
118 49 55.82W<br />
47 03 48.10N<br />
119 44 38.98W<br />
38 46 57.11N<br />
112 29 43.98W<br />
35 19 18.31N<br />
114 48 16.88W<br />
FUNCTION<br />
EMISSION<br />
DELAY<br />
THEORETICAL<br />
BASELINE<br />
TRAVEL TIME (3)<br />
RADIATED<br />
PEAK<br />
POWER<br />
MASTER — — 400 kW<br />
W<br />
SECONDARY<br />
13796.90 m s 2796.90 m s 1400 kW<br />
X SECONDARY 28094.50 m s 1094.50 m s 400 kW<br />
Y SECONDARY 41967.30 m s 1967.30 m s 560 kW<br />
(1) This station operated by United States of America.<br />
(2) Based on WGS 84 Datum (Coordinate system for charting).<br />
(3) Theoretical Baseline Travel Time is based on all-seawater transmission path between master and secondary.<br />
TABLE 4<br />
NORTH CENTRAL U.S. LORAN-C CHAIN – GRI 8290<br />
STATION<br />
HAVRE,<br />
Montana (1)<br />
BAUDETTE,<br />
Minnesota (1)<br />
GILLETTE,<br />
Wyoming (1)<br />
WILLIAMS LAKE,<br />
BC<br />
LATITUDE<br />
LONGITUDE<br />
(2)<br />
48 44 38.59N<br />
109 58 53.613W<br />
48 36 49.95N<br />
94 33 17.92W<br />
44 00 11.1N<br />
105 37 23.90W<br />
51 57 58.88N<br />
122 22 01.69W<br />
FUNCTION<br />
EMISSION<br />
DELAY<br />
THEORETICAL<br />
BASELINE<br />
TRAVEL TIME (3)<br />
RADIATED<br />
PEAK<br />
POWER<br />
MASTER — — 400 kW<br />
W<br />
SECONDARY<br />
14786.56 m s 3786.56 m s 800 kW<br />
X SECONDARY 29084.44 m s 2084.44 m s 400 kW<br />
Y SECONDARY 45171.62 m s 3171.62 m s 400 kW<br />
(1) This station operated by the United States of America.<br />
(2) Based on WGS 84 (coordinate system for charting).<br />
(3) Theoretical Baseline Travel Time is based on all-seawater transmission path between master and secondary.<br />
Loran-C Coordinate Converters<br />
Many of the Loran-C Coordinate Converters on the market do not compensate for the overland propagation errors caused<br />
by radio waves travelling more slowly over land than they do over seawater. These converters assume that the radio<br />
waves are travelling over an all seawater path from the transmitters to the ship. Because the amount of the time delay in<br />
each pattern varies with location, as does the width for 1 microsecond in each pattern, and the angle of cut between<br />
patterns, and which two patterns are being used for the position determination, there can be no over-all simple error<br />
statement.<br />
It is important to note that a Loran-C coordinate converter that does not incorporate the overland propagation corrections<br />
(Additional Secondary Factor, or ASF) within its computations will produce a systematic geographic position error. This<br />
error is often in the dangerous direction; namely, it will compute a position that is farther offshore. If you are transiting<br />
along a coast, thinking that you are safely outside the dangerous shoals, you may find yourself closer to shore than you<br />
think you are.<br />
The <strong>Canadian</strong> Hydrographic Service (CHS) has determined the overland propagation (ASF) errors through actual<br />
observations. The overland propagation corrections were incorporated into the lattices that were/are on CHS nautical<br />
charts. These maps have been published maps showing the corrections to observed Time Differences (TDs) necessary to<br />
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